Hi Iv just had my 4 year old gold fish die and a week before I got him a friend who is now sick. There must be something wrong with my tank . Maybe it's black algae which ️iv been trying to treat. Although iv been told that it's harmless . It's a 45l tank with one fancy goldfish . Tests seem normal although GH seems a little high. I'm treating for swim bladder and giving salt baths because I don't no what else to do. I Want to do Epsom salts incase it's dropsy but is it a bad idea if GH is high. He's spitting peas out and often liying on his side. When in salt water he looks like he's got dropsy with out the bloating and his gills go crazy.There are bubbles in the tank and yesterday I did a 25% water change with tap conditioner . And anoth small one today He's not so floppy today but this gasping when he sees me is new. Also had slight spasms earlier